The present invention relates to motion control systems used, for example, in rotary and linear brushless direct current motors. More particularly, the present invention relates to a power supply for such systems.
In many motion control systems, electrical power is commonly provided with high voltage alternating current (AC) or direct current (DC). The high voltage electrical power is used to power a motor or other power consuming device. In a motor, an inverter receives electrical power at a first DC voltage level and selectively provides power to windings of the motor based on command signals from a controller. The controller includes a control circuit comprising low level logic devices and a power supply. The power supply commonly converts the high voltage power to a low voltage level suitable for operation of the logic devices. Unfortunately, when high voltage power is cut or turned off, so is the power to the controller. Therefore, auxiliary power is generally provided once the high voltage has been turned off. Unfortunately, with the momentary loss of power to the controller, operating conditions have changed, which may complicate diagnostic analysis if the controller is malfunctioning.
In addition, the position of the moving member is typically lost with power removal, which requires the operator to perform a "homing" operation in order to reestablish the moving member in a known position with respect to the system. Although the homing operation or procedure properly positions the moving member with respect to the system, the homing procedure increases the downtime of the system.
Accordingly, there is a need for a system to provide continuous power to the motion control system.